UN nuclear inspectors have started a three-day mission to examine Iran's atomic activities. Tehran says it's certain the talks - the first in more than three years - will prove its program's purpose is purely peaceful. The IAEA visit comes at a time when tensions between Iran and the West are approaching crisis level. On Monday, EU nations adopted an unprecedented set of sanctions against the Islamic Republic, which include a complete embargo on oil supplies from Iran. That comes into force in July, but Iran is considering an immediate halt of oil sales to Europe in retaliation. RT discusses the latest development around the Iranian crisis with Seyed Mohammad Marandi, who's a professor at the University of Tehran.